A typical positive displacement fluid pump referred to generically as a "crescent gear pump" or "crescent pump" includes a housing having an inlet port and a discharge port, a driving gear rotatable on the housing about a first centerline, and a driven gear rotatable on the housing about a second centerline parallel to and laterally separated from the first centerline. External gear teeth on the driving gear mesh with internal gear teeth on the driven gear between the inlet and the discharge ports to isolate the discharge port from the inlet port in the direction of rotation of the driving and the driven gears. External and internal troughs on the driving and the driven gears between the gear teeth thereon define pump chambers in which fluid is transferred from the inlet port to the discharge port. A stationary crescent-body between the driving gear and the driven gear has a pair of arc-shaped walls which fit closely around the driving and the driven gears and cooperate with the tips of the external and the internal gear teeth thereon in defining fluid seals against fluid leakage from the discharge port to the inlet port. Pressure pulses attributable to succeeding ones of such pump chambers closing abruptly at an upstream end of the crescent body and opening abruptly at a downstream end thereof and to similarly abrupt closing and opening of trapped volumes between successive pairs of meshed external and internal gear teeth exert dynamic pressure forces on the driving gear which contribute to audible vibration of the crescent pump.